Right now, the effects of skills are incredibly easy to ignore, not because they are not severe enough, but because those effects are mostly hidden from players and very easy for them to not think about. The only thing you see on the project initiation page is how long the project will take the average person, not how long it will take you relatively. The only way you will notice the effects is if you're paying attention, remember when you started a project, and then the next day remember when you started it and say "hey! I started this project 9 hours ago and it said it should take 8 and I'm not even near done yet!
Outside of that, the only way people know what the effects of the skill system are is if they read the wiki and all of the updates. I bet some novice players may think the times are more or less randomized. Even once you understand what effects they have, you're not going to remember the unique skill set combinations across 5-15 characters. You would have to check your character page every time you consider starting a certain type of project.
It is cognitively taxing to be checking and thinking about that all the time, so people are likely to simply ignore it instead. Until the effects of skills are made more obvious, giving them more equally non-obvious effects are probably not going to change the way that people act.
So, maybe it would be good idea to showing player how long they will work at project in real (including character skill, tired lvl, health) ?